Pipe centering and washing apparatus

ABSTRACT

A pipe centering and washing apparatus comprises a body having an axial bore sized to accommodate a drill string, and pipe moving means. The pipe moving means comprises a ram housing having a radial bore, a pipe ram movable along the radial bore, and a ram actuator to move the pipe ram along the radial bore. When the pipe centering and washing apparatus is mounted on the wellhead, the axial bore is in fluid communication and substantially aligned with the wellhead&#39;s internal bore. The pipe centering and washing apparatus is operable between a retracted position and a centering position. When a drill string is present in the axial bore, the pipe moving means is operable to position the drill string in the axial bore between an off-centered position and a substantially centered position.

FIELD OF THE INVENTION

This invention relates generally to positioning and cleaning drill strings, tubulars, pipes and the like. More particularly, the invention relates to a system and apparatus for positioning and cleaning drill strings, tubulars, pipes and the like adjacent an oil or gas wellhead.

BACKGROUND OF THE INVENTION

The background information discussed below is presented to better illustrate the novelty and usefulness of the present invention. This background information is not admitted prior art.

In the oil and gas industry it is increasingly common practice for the wellbore to be inclined at some non-vertical angle so that the wellbore penetrates the fluid producing strata along a lengthened path, thus providing the wellbore with greater exposure to the producing formation. Directional drilling allows wells to be completed down hole at angles up to and including 90 degrees from vertical. Depending on the well depth, it may be necessary that the wellhead is also inclined relative to the vertical axis or vertical plane. Such is often the case in shallow wells with near horizontal downhole completion angle or when surface topology prohibits drilling the well from directly above the producing formation. The range of surface inclination for such inclined or angled wellheads typically varies between 0 and 45 degrees from vertical.

Non-vertical wellheads present problems for traditional surface-deployed pressure control equipment, such as blowout preventers (BOP) or blowout preventer stacks having a plurality of rams and/or annulars. This is because, from a load, alignment and pressure sealing standpoint, such pressure control equipment is based upon a fundamental assumption of vertical operation through the axial bore of such pressure control equipment, i.e. with the longitudinal axis of the pipe or drill string being substantially aligned with the vertical plane (relative to the ground) and substantially centered within said axial wellbore.

However, when running drill string or pipe through a non-vertical, angled wellhead and pressure control equipment, gravity will pull the pipe or drill string off-center towards the lowest portion of the axial borehole; see FIGS. 1A-1C. Such off-center orientation may make it difficult for the rams or annulars of a blowout preventer to properly seal against the drill string or pipe. Lack of a proper seal can lead to a potentially catastrophic event known as a blowout. It has therefore been common practice to send a worker, such as a roughneck or floorhand, to manually push or maneuver the drill string or pipe to a more centralized position within the BOP's axial bore.

Such manual positioning may work in some instances. However, in cases where the pressure control equipment must seal quickly (e.g. to deal with an unexpected formation kick), this practice puts such worker directly in the area of the well where a blowout may occur, i.e. directly adjacent the dangerous area. Moreover, when pipe or drill string is retrieved or pulled out of the wellbore, the pipe or drill string is dirty and greasy. This is undesirable, since workers who manually handle the pipe and drill string (e.g. to center the drill string) may not be able to obtain a proper grip on the pipe or drill string.

Therefore, what is needed is a tool, apparatus or system that can re-center drill string or pipe that is in an off-center orientation within the axial bore of the pressure control equipment and, preferably, can also clean off any dirt or grease that may be on the drill string or pipe as it is retrieved from wellbore.

SUMMARY OF THE INVENTION

In one aspect there is provided a pipe centering and washing apparatus for use with a wellhead having an internal bore. The pipe centering and washing apparatus comprises a body having an axial bore sized to accommodate a drill string and pipe moving means. The pipe moving means comprises at least one ram housing having a radial bore, at least one pipe ram movable along the radial bore, and at least one ram actuator to move the pipe ram along the radial bore. When the pipe centering and washing apparatus is mounted on the wellhead, the axial bore is in fluid communication and substantially aligned with the wellhead's internal bore. The pipe centering and washing apparatus is operable between a retracted position and a centering position. When a drill string is present in the axial bore, the pipe moving means is operable to position the drill string in the axial bore between an off-centered position and a substantially centered position.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the figures, wherein:

FIGS. 1A-1C are perspective, side and sectioned-side views of a PRIOR ART blowout preventor (BOP) stack mounted on an angled or inclined wellhead and showing the drill string located off-center inside the BOP's main inner bore;

FIGS. 2A-2C are perspective, side and sectioned-side views of one embodiment of a pipe centering and washing apparatus in a non-actuated state, mounted between a wellhead and BOP stack, wherein the drill string is off-center inside the BOP's main inner bore;

FIGS. 3A-3C are perspective, side and sectioned-side views of the pipe centering and washing apparatus the embodiment of FIG. 2A in an actuated state, mounted between a wellhead and BOP stack, wherein the drill string is centered inside the BOP's main inner bore;

FIGS. 4A-4I are various perspective and sectioned views of the pipe centering and washing apparatus the embodiment of FIG. 2A in a non-actuated state, wherein the drill string is off-center inside the BOP's main inner bore;

FIGS. 5A-5C are sectioned side perspective views of the pipe centering and washing apparatus the embodiment of FIG. 2A, in a non-actuated state, a partially actuated state and a fully actuated state, respectively;

FIGS. 6A-6C are sectioned side perspective views of the pipe centering and washing apparatus the embodiment of FIG. 2A, in a non-actuated state, a partially actuated state and a fully actuated state, respectively;

FIGS. 7A-8C are sectioned top views of various embodiments of the pipe centering and washing apparatus, all shown in an actuated state, with the drill string or pipe in a substantially centered position;

FIGS. 9A-11C are various views of various embodiments of the ram stop;

FIG. 12 is a top section view of another embodiment of the pipe centering and washing apparatus, illustrating a preferred spray pattern of cleaning fluid on a pipe; and

FIGS. 13A-13C are perspective views of yet another embodiment of the pipe centering and washing apparatus, illustrating cleaning fluid being sprayed on a pipe.

DEFINITION SECTION

Horizontal plane, as used herein, refers to a plane that is horizontal at a given point if it is perpendicular to the gradient of the gravity field at that point, in other words, apparent gravity is what makes a plumb bob hang perpendicular to the plane at that point. In other words a horizontal plane in the plane that is perpendicular to the line that passes through the center of the Earth.

Vertical axis, as used herein, refers to a direction passing by a given point if it is locally aligned with the gradient of the Earth's gravity field, i.e., with the direction of the gravitational force (per unit mass, i.e. gravitational acceleration vector) at that point.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is of preferred embodiments by way of example only and without limitation to the combination of features necessary for carrying the invention into effect. Reference is to be had to the Figures in which identical reference numbers identify similar components. The drawing figures are not necessarily to scale and certain features are shown in schematic or diagrammatic form in the interest of clarity and conciseness.

A first embodiment of the pipe centering and washing apparatus 10 of the present invention is shown in FIGS. 2A-6C and is designed to be installed on, and supported by, a wellhead W that comes out of, or is above, the ground surface G. The ground G may be along the horizontal plane H, or it may have an irregular contour. The apparatus 10 is preferably mounted adjacent to, or is included as part of, the well's pressure control equipment, such as a blowout preventer stack B; see FIGS. 2A-3C. The wellhead W may be offset or inclined from the vertical axis V, with typical angles A of such inclination varying between 0 and 45 degrees from the vertical axis V. The wellhead W and any pressure control equipment (such as blowout the preventer stack B) each have an internal bore BH sufficiently large to permit the passage of the drill string or pipe P there through into or out of a wellbore (not shown). The wellbore is fluidly connected the wellhead W and pressure control equipment B via the internal bore(s) BH.

The pipe centering and washing apparatus 10 comprises a body or housing 12 having an axial bore 12 b. When the apparatus 10 is mounted on a wellhead W, the axial bore 12 b is in fluid communication and aligned with the wellbore and the internal bore(s) BH of the wellhead W and any pressure control equipment B; see FIGS. 2A-3C. The axial bore 12 b is of sufficient size and dimensions to accommodate the drill string or pipe P that passes through the internal bore(s) BH of the wellhead W and any pressure control equipment B.

Preferably, the apparatus 10 is designed to American Petroleum Institute (API) standards for the particular design criteria of the wellbore including wellbore pressures and fluid characteristics. The body 12 is mounted to the wellhead W and any pressure control equipment B in a conventional manner so as to contain any wellbore pressures, directing such pressures and any wellbore fluids to travel through the fluid connection between axial bore 12 b and internal bore(s) BH of the wellhead W and pressure control equipment B. Body 12 is preferably an API flange or spool. More preferably, body 12 is a rotating flange.

The pipe centering and washing apparatus 10 may be actuated between an operably retracted position RP (e.g. FIGS. 2A-2C, 4A-4I, 5A and 6A) and an operably centering position CP (e.g. FIGS. 3A-3C, 5C and 6C). When the apparatus 10 is actuated to the centered position CP, the apparatus 10 substantially centers any drill string or pipe P inside the body's main axial bore 12 b (see FIGS. 5C and 6C) and hence, also in the internal bores BH of the wellhead W and pressure control equipment B (see FIG. 3C). Advantageously, the rams or annulars of a blowout preventer B can then properly seal against the drill string or pipe P when the pressure control equipment B is engaged to control pressure within the wellbore. More advantageously, a worker will not have to manually push or maneuver the drill string or pipe P (to a more centralized position within the BOP's axial bore BH), thereby preventing such worker from having to go to a potentially dangerous place where a blowout may occur.

The pipe centering and washing apparatus 10 preferably comprises at least one ram housing 20 having a radial bore 20 b, at least one pipe ram 30 and at least one ram actuator 40. Pipe ram 30 is suitable to position or move drill string or pipe P from an off-centered position O within axial bore 12 b (when the apparatus 10 is in the retracted position RP, e.g. FIG. 6A) to a substantially centered position C within axial bore 12 b (when the apparatus 10 is in the centered position CP, e.g. FIG. 6C). Preferably, pipe ram 30 has a pipe engaging end 30 e with a suitable curvature so as to easily capture and center pipe P within bore 12 b. A suitable pipe ram 30 has an end 30 e that has a width (or pipe engaging surface) that measures between 25% to 65% of the diameter of the bore 12 b. More preferably, pipe engaging end 30 e has a surface covering which suitable to engage pipe P without causing significant damage to said pipe. Even more preferably, radial bore 20 b is of such size and dimensions to fully accept pipe ram 30 (and curved end 30 e) when the apparatus 10 is in the retracted position RP (see: FIGS. 4D-4H, 6A). Advantageously, when in the retracted position RP, axial bore 12 b is unobstructed and any drill string or pipe P can freely travel from the wellhead W to the pressure control equipment B, without catching on pipe ram 30.

Apparatus 10 may be provided with addition radial bores or ports 25, to provide an operator with additional access to the bore 12 b and wellbore BH. It is contemplated that such additional radial bores 25 may function as kill line outlets or choke line outlets for the well. When not in use, such additional radial bores 25 may be closed with a suitable closure plug or the like (not shown).

Preferably, during operation, apparatus 10 is mounted to the wellhead W and pressure control equipment B so that: (i) axial bore 12 is substantially aligned with the internal bores BH of the wellhead W and pressure control equipment B and (ii) the ram housing 20, radial bore 20 b and ram actuator 40 are oriented to allow pipe ram 30 to act or push against the drill string or pipe P in a direction that will substantially overcome the relevant force(s) of gravity that may have caused the drill string or pipe P to be in an off-centered position O, so as to then move the drill string or pipe to a substantially centered position C within bore 12 b. In the embodiment shown in FIGS. 2A-3A, ram housing 20, radial bore 20 b and ram actuator 40 are oriented below the drill string or pipe P, to allow pipe ram 30 to engage the drill string or pipe P from below.

More preferably, the longitudinal axis 20 x of radial bore 20 b is aligned substantially perpendicular (90 degrees) to the axis 12 x of the body's axial bore 12 b (see: FIG. 4F). Advantageously, this will allow easy orientation of the ram housing 20, radial bore 20 b and ram actuator 40 to a desired position; by rotating the apparatus 10 around the axial bore 12 b. More preferably, body 12 is a rotating or swivel flange, to further facilitate such rotation.

The pipe ram 30, and the actuation thereof, is insensitive to the size of the drill string or pipe P and ram actuator 40 may be any suitable actuator that meets the relevant API standards and criterial. A suitable ram actuator 40 is a conventional double-acting hydraulic ram 60 having a piston 61 in a cylinder 62. See, for example, FIG. 4D. The piston 61 is operatively connected to the pipe ram 30, such as through a piston rod 63 having a proximal end 63 a connected to the pipe ram 30 in a conventional manner. Piston rod 63 may have a distal end 63 b (generally opposing proximal end 63 a) which extends out through ram housing 20 and actuator 40. Preferably, one or more piston rod seals S are positioned between the ram housing 20/actuator 40 and the piston rod 63 wherein any fluids and pressures in the radial bore 20 b and wellbore are contained and further are isolated from the actuator 40 and from the external environment. Ports 64 are provided at opposing ends 65, 66 of the cylinder 62 for connection to suitable hosing and a control valve (not illustrated) as understood by one of skill in the art, and which can be actuated remotely.

As can be appreciated by those skilled in the art, the amount of actuation or stroke that the pipe ram 30 may need to make (along radial bore 20 b) in order to position or move drill string or pipe P from an off-centered position O to a substantially centered position C will depend on the diameter of the axial bore 12 b and the diameter of the drill string or pipe P. As can also be appreciated, pipe P of various diameters may be positioned in, or moved through, a particular axial bore 12 b. For example, if a pipe P with a small diameter is placed in axial bore 12 b, then pipe ram 30 may need to travel or stroke further (along radial bore 20 b and into axial bore 12 b), as compared to if the pipe P has a larger diameter. For example compare FIG. 8A (wherein the pipe P has a smaller diameter) to FIG. 8C (wherein the pipe P has a larger diameter). The pipe ram 30 in FIG. 8A will travel or stroke further than in FIG. 8C.

To allow the apparatus 10 to easily accommodate drill string or pipe P of various diameters, a removable ram stops 100 may be provided at the distal end 63 b of rod 63 to limit the stroke of the pipe ram 30 (along radial bore 20 b and into axial bore 12 b) to a predetermined position. Preferably, ram stop 100 comprises a central axial shaft member 100 s which treadably engages a threaded opening 63 o at distal end 63 b of shaft 63 (threads not shown), so as to removable mount or connect the ram stop 100 to the distal end 63 b. More preferably, ram stop 100 further comprises a member 100 c that positions or wraps around the outside of the shaft's distal end 63 b. Member 100 c may be a circumferential member which fully wraps around end 63 b, or it may be so other member that only partially covers end 63. When actuating the apparatus 10 to the centering position CP, member 100 c will engage end 66 of the cylinder 62, thereby stopping shaft 63 (and ram 30) from moving any further into bore 20 b and settling at the predetermined position; see FIG. 8A-9C.

By adjusting the dimensions of member 100 c, a particular ram stop 100 will stop the pipe ram 30 at a particular predetermined stroke position. The apparatus 10 may be provided with a plurality of ram stop 100, each with member 100 c of a different dimension and each suitable to stop pipe ram 30 at a centering position CP for a particular sized/diameter pipe P. Compare, for example, ram stop 100 in FIG. 8A to ram stop 100 in FIG. 8C (or the ram stop 100 in FIGS. 10A-10C to the one in FIGS. 11A-11C). Member 100 c in FIG. 8A is significantly shorter than member 100 c in FIG. 8C, and will allow rod 63 and ram 30 to travel further down bore 20 b and into bore 12 b. Accordingly, the embodiment of ram stop 100 in FIG. 8A is more suitable for smaller diameter pipe P, than the embodiment of FIG. 8C (which is more suitable for larger diameter pipe P and will stop the stroke of rod 63 and pipe ram 30, sooner).

Advantageously, in order to allow apparatus 10 to easily accommodate pipe P of various dimensions, all that needs to be done is to remove one ram stop 100 (used for a previous pipe P) and exchange it with another ram stop 100 that is preset for the diameter of the new pipe P.

Preferably, the apparatus 10 is provided with one or more cleaning fluid passages 120 and nozzles 130, to allow an operator to spray a cleaning fluid CF (e.g. water) onto a pipe P as said pipe P is being removed from the wellbore and wellhead W. Preferably passages 120 and nozzles 130 are provided in a radial manner around bore 12 b (see: FIGS. 4C, 12). Anywhere from 4 to 8 such passages and nozzles have been found to be desirable and sufficient to clean a pipe P. More preferably, nozzles 130 are provided in a circumferential groove 12 g within bore 12 b, so as to not interfere with any pipe P that may be moving through said bore. Even more preferably, suitable conduits 140 (hoses or pipes) provide fluid communication between a source of cleaning fluid CF (not shown) and the nozzles 120.

Those of ordinary skill in the art will appreciate that various modifications to the invention as described herein will be possible without falling outside the scope of the invention. In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite article “a” before a claim feature does not exclude more than one of the features being present. 

The embodiments of the invention in which an exclusive property or privilege is being claimed are defined as follows:
 1. A pipe centering and washing apparatus for use with a wellhead having an internal bore, the pipe centering and washing apparatus comprising: a body having an axial bore being sized to accommodate a drill string; a pipe moving means, comprising: at least one ram housing having a radial bore; at least one pipe ram movable along the radial bore; and at least one ram actuator to move the pipe ram along the radial bore; wherein, when the pipe centering and washing apparatus is mounted on the wellhead, the axial bore is in fluid communication and substantially aligned with the wellhead's internal bore; wherein the pipe centering and washing apparatus is operable between a retracted position and a centering position; and wherein, when a drill string is present in the axial bore, the pipe moving means is operable to position the drill string in the axial bore between an off-centered position and a substantially centered position.
 2. The pipe centering and washing apparatus of claim 1 wherein the body is a rotating flange.
 3. The pipe centering and washing apparatus of claim 1 wherein the pipe ram further comprises a pipe engaging end having a width that measures between 25% to 65% of the diameter of the axial bore.
 4. The pipe centering and washing apparatus of claim 1 wherein the radial bore is sized to fully receive the pipe ram therein when the pipe centering and washing apparatus is in the retracted position.
 5. The pipe centering and washing apparatus of claim 1 wherein the body further comprises additional radial bores in fluid communication with the axial bore.
 6. The pipe centering and washing apparatus of claim 1 wherein the ram actuator further comprises a double-acting hydraulic ram having a piston in a cylinder, said piston connected to the pipe ram by means of a piston rod; wherein the piston rod comprises a proximal end and a distal end; wherein the piston connects to the pipe ram at said proximal end; and further comprising at least one removable ram stop operable to connect to said distal end and sized to limit the stroke of the ram actuator to a predetermined position.
 7. The pipe centering and washing apparatus of claim 6 wherein the distal end comprises a threadable opening; wherein the at least one removable ram stop further comprises: a central axial shaft member suitable to threabably connect to the threaded opening; and a circumferential member dimensioned to engage the piston when the stroke of the ram actuator is in the predetermined position.
 8. The pipe centering and washing apparatus of claim 1 wherein the body further comprises at least one fluid passage having at least one nozzle; wherein the fluid passage is suitable to direct a cleaning fluid from an exterior source into the axial bore via said at least one nozzle.
 9. The pipe centering and washing apparatus of claim 8 wherein a plurality of fluid passages and a plurality of nozzles are provided in a radial manner around the axial bore.
 10. The pipe centering and washing apparatus of claim 9 further comprising a circumferential groove along the interior of the body; and wherein said plurality of nozzles are all positioned entirely within said circumferential groove.
 11. A pipe centering and washing apparatus for use with a wellhead having an internal bore, the pipe centering and washing apparatus comprising: a body having an axial bore being sized to accommodate a drill string; a pipe moving means, comprising: at least one ram housing having a radial bore; at least one pipe ram movable along the radial bore; and at least one ram actuator to move the pipe ram along the radial bore; wherein, when the pipe centering and washing apparatus is mounted on the wellhead, the axial bore is in fluid communication and substantially aligned with the wellhead's internal bore; wherein the pipe centering and washing apparatus is operable between a retracted position and a centering position; wherein, when a drill string is present in the axial bore, the pipe moving means is operable to position the drill string in the axial bore between an off-centered position and a substantially centered position; wherein the radial bore is sized to fully receive the pipe ram therein when the pipe centering and washing apparatus is in the retracted position; and wherein the ram actuator further comprises a double-acting hydraulic ram having a piston in a cylinder, said piston connected to the pipe ram by means of a piston rod; wherein the piston rod comprises a proximal end and a distal end; wherein the piston connects to the pipe ram at said proximal end; and further comprising at least one removable ram stop operable to connect to said distal end and sized to limit the stroke of the ram actuator to a predetermined position.
 12. The pipe centering and washing apparatus of claim 11 wherein the body further comprises at least one fluid passage having at least one nozzle; wherein the fluid passage is suitable to direct a cleaning fluid from an exterior source into the axial bore via said at least one nozzle.
 13. The pipe centering and washing apparatus of claim 12 wherein a plurality of fluid passages and a plurality of nozzles are provided in a radial manner around the axial bore.
 14. The pipe centering and washing apparatus of claim 13 further comprising a circumferential groove along the interior of the body; and wherein said plurality of nozzles are all positioned entirely within said circumferential groove.
 15. The pipe centering and washing apparatus of claim 11 wherein the body is a rotating flange.
 16. The pipe centering and washing apparatus of claim 11 wherein the pipe ram further comprises a pipe engaging end having a width that measures between 25% to 65% of the diameter of the axial bore. 